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What an unprocessed photo looks like

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Re: What an unprocessed photo looks like

#31

Post by jeeyoungk »

XCSme wrote: post #20
ranger207 wrote: post #18

Earlier quoted context omitted.

It's a single value per pixel, but each pixel has a different color filter in front of it, so it's effectively that each pixel is one of R, G, or B

So, for a 3x3 image, the input data would be 9 values like: R G B B R G G B R ?

If you want "3x3 colored image", you would need 6x6 of the bayer filter pixels.

Each RGB pixel would be 2x2 grid of

``` G R B G ```

So G appears twice as many as other colors (this is mostly the same for both the screen and sensor technology).

There are different ways to do the color filter layouts for screens and sensors (Fuji X-Trans have different layout, for example).

Re: What an unprocessed photo looks like

#32

Post by i-am-gizm0 »

XCSme wrote: post #13

I am confused by the color filter step. Is the output produced by the sensor RGB or a single value per pixel?

The raw sensor output is a single value per sensor pixel, each of which is behind a red, green, or blue color filter. So to get a usable image (where each pixel has a value for all three colors), we have to somehow condense the values from some number of these sensor pixels. This is the "Debayering" process.

Re: What an unprocessed photo looks like

#33

Post by to11mtm »

stavros wrote: post #6
userbinator wrote: post #5

I think everyone agrees that dynamic range compression and de-Bayering (for sensors which are colour-filtered) are necessary for digital photography, but at the other end of the spectrum is "use AI to recognise objects and hallucinate what they 'should' look like" --- and despite how everyone would probably say that isn't a real photo anymore, it seems manufacturers are pushing strongly in that direction, raising iss…

One thing I've learned while dabbling in photography is that there are no "fake" images, because there are no "real" images. Everything is an interpretation of the data that the camera has to do, making a thousand choices along the way, as this post beautifully demonstrates. A better discriminator might be global edits vs local edits, with local edits being things like retouching specific parts of the image to make d…

Well that's why back in the day (and even still) 'Photographer listing their whole kit for every shot' is a thing thing you sometimes see.

i.e. Camera+Lens+ISO+SS+FStop+FL+TC (If present)+Filter (If present). Add focus distance if being super duper proper.

And some of that is to help at least provide the right requirements to try to recreate.

Re: What an unprocessed photo looks like

#34

Post by stefan_ »

steveBK123 wrote: post #21
XCSme wrote: post #13

I am confused by the color filter step. Is the output produced by the sensor RGB or a single value per pixel?

In its most raw form, camera sensors only see illumination not color. In front of the sensor is a bayer filter which results in each physical pixel seeing illumination filtered R G or B. From there the software onboard the camera or in your RAW converter does interpolation to create RGB values at each pixel. For example if the local pixel is R filtered, it then interpolates its G & B values from nearby pixels of that…

B&W sensors are generally more sensitive than their color versions, as all filters (going back to signal processing..) attenuate the signal.

Re: What an unprocessed photo looks like

#36

Post by barishnamazov »

delecti wrote: post #23
barishnamazov wrote: post #7

I love posts that peel back the abstraction layer of "images." It really highlights that modern photography is just signal processing with better marketing. A fun tangent on the "green cast" mentioned in the post: the reason the Bayer pattern is RGGB (50% green) isn't just about color balance, but spatial resolution. The human eye is most sensitive to green light, so that channel effectively carries the majority of t…

I have a related anecdote. When I worked at Amazon on the Kindle Special Offers team (ads on your eink Kindle while it was sleeping), the first implementation of auto-generated ads was by someone who didn't know that properly converting RGB to grayscale was a smidge more complicated than just averaging the RGB channels. So for ~6 months in 2015ish, you may have seen a bunch of ads that looked pretty rough. I think I…

I don't think Kindle ads were available in my region in 2015 because I don't remember seeing these back then, but you're a lucky one to fix this classic mistake :-)

I remember trying out some of the home-made methods while I was implementing a creative work section for a school assignment. It’s surprising how "flat" the basic average looks until you actually respect the coefficients (usually some flavor of 0.21R + 0.72G + 0.07B). I bet it's even more apparent in a 4-bit display.

Re: What an unprocessed photo looks like

#38

Post by itishappy »

XCSme wrote: post #25
steveBK123 wrote: post #21

Earlier quoted context omitted.

In its most raw form, camera sensors only see illumination not color. In front of the sensor is a bayer filter which results in each physical pixel seeing illumination filtered R G or B. From there the software onboard the camera or in your RAW converter does interpolation to create RGB values at each pixel. For example if the local pixel is R filtered, it then interpolates its G & B values from nearby pixels of that…

What about taking 3 photos while quickly changing the filter (e.g. filters are something like quantum dots that can be turned on/off)?

> What about taking 3 photos while quickly changing the filter

Works great. Most astro shots are taken using a monochrome sensor and filter wheel.

> filters are something like quantum dots that can be turned on/off

If anyone has this tech, plz let me know! Maybe an etalon?

https://en.wikipedia.org/wiki/Fabry%E2%80%93P%C3%A9rot_inter...

Re: What an unprocessed photo looks like

#39

Post by dheera »

barishnamazov wrote: post #7

I love posts that peel back the abstraction layer of "images." It really highlights that modern photography is just signal processing with better marketing. A fun tangent on the "green cast" mentioned in the post: the reason the Bayer pattern is RGGB (50% green) isn't just about color balance, but spatial resolution. The human eye is most sensitive to green light, so that channel effectively carries the majority of t…

This is also why I absolute hate, hate, hate it when people ask me whether I "edited" a photo or whether a photo is "original", as if trying to explain away nice-looking images as if they are fake.

The JPEGs cameras produce are heavily processed, and they are emphatically NOT "original". Taking manual control of that process to produce an alternative JPEG with different curves, mappings, calibrations, is not a crime.

Re: What an unprocessed photo looks like

#40

Post by XCSme »

itishappy wrote: post #38
XCSme wrote: post #25

Earlier quoted context omitted.

What about taking 3 photos while quickly changing the filter (e.g. filters are something like quantum dots that can be turned on/off)?

> What about taking 3 photos while quickly changing the filter Works great. Most astro shots are taken using a monochrome sensor and filter wheel. > filters are something like quantum dots that can be turned on/off If anyone has this tech, plz let me know! Maybe an etalon? https://en.wikipedia.org/wiki/Fabry%E2%80%93P%C3%A9rot_inter...

> If anyone has this tech, plz let me know!

I have no idea, it was my first thought when I thought of modern color filters.

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